The present invention is related to the field of agro-products, pharmaceutical production, and sample analysis and, more particularly, to pressurized liquid extraction systems.
In the field of sample analysis, a large variety of studies are conducted in order to monitor the presence of contaminants in food. In particular, antitoxins and toxins such as brominated and chlorinated compounds, pesticides, PCBs, PAHs, PBDE, and dioxins are extracted, purified and fractionated from pharmaceutical, environmental, and biological samples. New and more stringent regulations regarding acceptable levels of these contaminants are continuously being adopted by federal and state governments and/or regulatory agencies, driving the development of analytical systems that are more accurate, reliable and commercially practical.
Important criteria in the development of such systems include the detection of more compounds, with lower detection limits, relatively high throughput, and efficiency. Currently, only a few laboratories can fulfill these emerging requirements.
Since chlorinated and brominated compounds are very toxic at sub-ppt (parts per trillion) and ppqt (parts per quadrillion) levels, the purification of these compounds becomes a difficult task in sample analysis. It is necessary, for example, to protect the sample from interfering compounds during the extraction, purification, and fractionation processes. Indeed, interfering compounds can be introduced from the air and surrounding environment.
For example, it is required to detect some PCBs in low ppt level in food samples. However, the background amount of PCBs in the ambient air and other laboratory surroundings may exceed the detection limits of the sample, so that the laboratories are unable to perform accurate testing. As a result, laboratory testing facilities are increasingly being forced to construct at great cost new, clean room laboratories having controlled environments. Consequently, testing for these highly toxic compounds in food is becoming very difficult, and fewer laboratories are able to perform this testing.
In the field of agro-products, extracted, purified, and separated end products are obtained, e.g., from spices, herbs, aromatic plants, and medicinal plants, for use in various end use applications such as cosmetics, flavors, medicines, perfumes, and so forth.
In the field of pharmaceutical production, compounds of interest are extracted, purified, and separated for use in producing drugs and supplements. These processes are similar to those used in sample analysis, although they are usually carried out on a grander scale, to provide a desired amount of end products.
For recent years, new extraction techniques have emerged that exhibit advantages such as lower solvent consumption, suitability for automation, and higher throughput for processing solid and semi-solid samples such as food samples. The purification or “clean-up” step has also evolved from the early use of semi-automated stages to more recent use of entirely automated systems suitable for preparing a large number of samples.
Thus, there is a continuing need for fast, efficient systems for performing high-quality sample analysis and pharmaceutical production. One such system is the subject of U.S. Pat. No. 6,783,668 to Shirkhan.
The Shirkhan patent discloses a system for pressurized liquid extraction (“PLE”) and purification of solid biological materials that contain trace amounts of substances that may be the subject of subsequent analysis or that may be used as an ingredient in a pharmaceutical end product. Exemplary uses of the system include, without limitation, the extraction, purification, and fractionation of trace substances such as antibiotics, pesticides, PCBs, PAHs, PBDE, pesticides, and chlorinated and brominated compounds.
More specifically, according to Shirkhan, extraction, purification, and fractionation are performed in a closed-loop system, which reduces the exposure of the sample to the air and to the surrounding environment. As a result, hundreds of toxins such as dioxins, PCBs, pesticides, and the like can be detected at relatively low concentration levels, e.g., ppqt, in a single run at generally high speed.
The Shirkhan system includes a pressurized liquid extraction (PLE) module having a solvent selection valve, a PLE cell, a heating element, a high-pressure pump, and a pressure regulator. The heating element is thermally coupled to the PLE cell, which includes an over temperature shut-off. The high-pressure pump is coupled to an input port of the PLE cell. The pressure regulator is coupled between an output port of the PLE module and an input port of the PLE cell. The output port of the cooling coil is coupled to the output port of the PLE module.
During operation, the cooling coil conditions the temperature of the extract and transfers the cooled extract to the input of a purification module. The PLE module continuously performs high-pressure, high-temperature extraction on the solid sample to yield a liquid sample, and concurrently provides the liquid sample to the output port of the PLE module for testing.
The Shirkhan system, which is manufactured by Fluid Management Systems, Inc. of Waltham, Mass., provides rapid detection of hundreds of the most toxic compounds in food. In addition, it reduces the need for clean room laboratories, which otherwise might be necessary to perform testing and detection of those toxins. The system, further, simplifies sample handling inside the laboratory.